The present invention relates to applying fluids to crop fields in the agricultural industry using a multiple distribution point applicator. More particularly, this invention relates to uniformly distributing and selectively outputting multiple fluid streams of a single or multiple-phase fluid from a fluid distributor manifold. More particularly, this invention relates to an improved method and system for distributing liquid fertilizer at a substantially equal rate to each of a plurality of distribution lines. The method and system of this invention facilitate more even distribution of fertilizer to each of the plurality of knives on an applicator.
Agricultural crop producers routinely apply liquid fertilizer to crop fields to replenish depleted nutrients beneficial to crop production. A common fertilizer used to replenish nitrogen in the soil is anhydrous ammonia (xe2x80x9cNH3xe2x80x9d). An applicator may include a plurality of selectively spaced xe2x80x9cknivesxe2x80x9d or xe2x80x9cshanks,xe2x80x9d which may be pulled through the soil at a selected depth, typically behind a farming tractor. A fertilizer application line may be positioned immediately behind each knife and extend nearly to the knife tip to release a selected amount of fertilizer into the soil as the knife is pulled through the soil. A disc may follow behind each knife and turn the soil to seal in the NH3 so it can mix with soil moisture to provide nitrogen to growing crops.
Fertilizer type and application rates may vary depending upon crop type. NH3 application rates may range from less than 40 pounds per acre to in excess of 200 ponds per acre. Applicators may include as few as 8 knives to in excess of 40 knives, and may be arranged across an applicator tool bar spanning a width of over 50 feet.
In a common arrangement, the bulk NH3 may be provided in a pressurized tank or xe2x80x9cnurse-bottlexe2x80x9d pulled behind the applicator. One or more high pressure hoses may function as a supply line to conduct NH3 from the nurse-bottle to one or more distributors.
The distributor may manifold the NH3 from a single supply line to each of a plurality of applicator lines, with each applicator line positioned substantially adjacent and behind a knife. NH3 may be conducted to the distributor through an inlet port positioned substantially within the center of an array of outlet ports. Unused ports may be plugged. The supply line, the applicator lines and the distributor may include a number of fittings, valves, obstructions, and changes of flow-direction, each of which may create a tortuous flow path and resultant pressure drops along the flow path.
Accurate and even application of anhydrous ammonia over the length of the applicator tool bar has been a significant problem which the farming industry has struggled to solve for many years. The fluid-phase state of NH3 is sensitive to each of pressure and temperature. NH3 may exist in a gas or vapor phase, a liquid phase, or both, depending upon the pressure and temperature conditions. Pressure drops may result in generation and/or expansions of a vapor phase. The vapor phase may consume a relatively high percentage of the available conduit volume and may be much more mobile or conductive, and thus more difficult to meter or control than the liquid phase. Devices commonly used to measure and divide the liquid to each knife may work well in a homogenous fluid streams, but may not perform well when random vapor pockets traveling within the liquid stream are encountered. Pockets of vapor may severely retard or impede liquid flow and/or measurement uniform distribution of anhydrous ammonia.
To provide greater distribution and application control and rate consistency between the knives, it is commonly more desirable to distribute liquid NH3 with no vapor to each of the application lines. The presence of a vapor phase within the distribution system may result in significant rate variability between knives. For example, some knives may be receiving two to four times more NH3 than other knives. Thereby, some crops may risk being burned, while others may be starved for nitrogen, the results of which may show up in crop yield, color and/or quality.
A number of products have been developed to improve liquid fertilizer distribution. One general group of distributors operates by generating a cyclone to create a vortex within the distributor and utilizes a vertical dam to segregate the liquid phase from the vapor phase. One such device is marketed by Continental NH3 Products, and is commonly referred to as a vertical dam manifold, as described in U.S. Pat. No. 5,372,160. The device may utilize interchangeable distribution rings that differ in the number of outlet holes and in the size of the outlet holes. In theory, one side of the dam is flooded with liquid while the other side of the dam contains the vapor phase. The liquid phase portion of the fertilizer is distributed to each of the plurality of applicator line outlets in an attempt to provide substantially equal rates of liquid to each applicator line. The vapor is allowed to rejoin the liquid streams downstream of the liquid distribution. A fluid back-pressure is preferably maintained upstream of the distribution ring, thereby maintaining a reduced vapor phase. A distributor providing small outlet ports may be required for low application rates, while a different distributor having larger outlet port sizes may be required for higher application rates. Although improved results may be obtained with such product as compared to more conventional distributors, results may reflect average application rate differences between knives in excess of 15% from the mean rate. Other devices using the cyclonic or spray principle are disclosed in U.S. Pat. Nos. 4,807,663, issued to Jones, and 4,284,243, issued to Shaner.
A second general group of prior art distributors uses rotors to mix or homogenize the two-phases into a mixture. U.S. Pat. No. 6,003,532 discloses a device that attempts to homogenize the two-phase vapor-liquid stream prior to distribution. The device uses a rotating flywheel driven by the incoming fluid to spin at a high velocity and sweep the incoming fluid rapidly past evenly spaced output holes on the inner surface of a distribution ring. The rapid sweeping action ideally homogenizes the mixture and thereby uniformly distributes the fertilizer. A desirable back-pressure is maintained by utilizing a distribution ring having appropriately sized outlet holes. Another device using the rotor technique is disclosed in U.S. Pat. No. 5,333,640, issued to Swift. Multiple distribution rings are thus generally required for a diversity of application ranges. Another drawback to this design is wear and maintenance of additional moving parts.
A third type of distributor utilizes a pump to increase fluid pressure in the distributor prior to distribution. Pressure may be increased to a level such that the pressure at each exit nozzle behind a respective knife may be greater than tank pressure. For example, injection pressure may be 150 psig, while tank pressure may be less than 120 psig. Thereby, the NH3 may remain in a liquid phase as it is conducted from the tank, through the system to the exit nozzle. Some additional pressure may be required to account for NH3 temperature increases within the system. The distributor may include a first arrangement of small-diameter distributor orifices that provide an appropriate regulation of rate at low application rates and speeds. A piston may be provided to move in response to increased pump pressure and/or applicator speed, exposing a second arrangement of distributor orifices having slightly larger diameters. Thereby, for a particular injection pressure the application rate may be increased. Such distributor system may be relatively expensive and maintenance intensive, requiring relatively complicated machining and expensive tooling on the piston, manifold and orifices. In addition, the pump is required, including means for powering, positioning, controlling, and maintaining the pump.
An improved method and system is desired for distributing liquid fertilizers substantially equally across the applicator bar. An improved method is desired which is economical and may be effective across a broad range of application rates and pressures without need for purchasing additional distributor equipment or pumps. The disadvantages of prior art are overcome by the present invention.
This invention has particular utility in applying fluid fertilizer, such as anhydrous ammonia (xe2x80x9cNH3xe2x80x9d), in an agricultural application. More particularly, this invention may improve distribution of a substantially equal amount of fertilizer to each of a plurality of applicator lines. The methods and apparatus of this invention provide a fertilizer distributor apparatus and system that improves fertilizer distribution rates and reduces rate variation between applicators. The improvement may be realized at least partially by distributing the fertilizer to each of the plurality of distributor lines substantially as a liquid phase, before creating or permitting fluid pressure-drops in the system. As discussed above, pressure drops may result in generation of a gas or vapor phase, which may result in variable distribution rates between applicator lines carrying a high percentage of gas phase and lines carrying a high percentage of liquid phase.
A fluid distributor is provided for receiving fluid fertilizer in an inlet and through a flow chamber, with substantially negligible pressure drops. Fluid in the flow chamber may be distributed to each of a plurality of distributor outlet ports, each connected to an applicator line, such that any substantial pressure drop may occur substantially during or downstream of the distribution. The applicator lines may dispose of the fluid fertilizer from within the lines into a respective row of earth, which may be mechanically broken and tilled to mix the fertilizer with the soil.
An adjustably positionable flow restrictor to permit a desired flow rate through the fluid distributor, and permits a corresponding fluid pressure drop in the distributed fluid. Selective movement of the flow restrictor may facilitate a substantially equal and corresponding adjustment in each of the plurality of applicator lines. Adjustment may vary substantially infinitely, from no-flow to full-open, substantially unrestricted flow in the applicator lines.
An object of the invention is to adjust the flow rate to each of a plurality of applicator lines such that a desired total fertilizer application rate may be maintained through the plurality applicator lines and at a substantially equal or uniform application rate in each of the plurality of applicator lines. Thereby, fertilizer application may be performed uniformly across the applicator bar at substantially any desired flow-rate, back-pressure and/or supply tank pressure.
The above objective may be facilitated by an adjustable orifice in the flow path to each applicator line, with the orifice located downstream or at the point of fluid distribution. Fertilizer distribution may be performed on a substantially liquid phase, while substantial pressure-drops may occur individually in the applicator lines after fluid distribution. The orifices may be collectively and uniformly adjusted to attain the maximum back pressure while still applying a desired fertilizer rate to the crops.
It is a further object of this invention to prevent occurrence of a significant vapor/gas phase upstream of fluid distribution. The maximum cumulative cross-sectional area of the flow areas at or downstream of the point of fluid distribution may be equal to or less than the maximum cross-sectional flow area of distributor inlet.
It is also an object of this invention to provide a distributor that may distribute a fluid fertilizer without substantial generation of vapors or gases, and which significantly reduces the fluid pressure only after distribution.
Yet another object of this invention is to provide a flow divider wherein the maximum cross-sectional flow area in the flow chamber between the inlet port and the outlet ports is no greater than a cross-sectional flow area at the supply inlet.
It is a feature of this invention to provide a fluid distributor including an inlet port, a plurality of outlet ports, a flow chamber between the inlet port and the plurality of outlet ports, and a flow restrictor adjusting the rate of fluid fertilizer through the fluid distributor.
It is an additional feature of this invention to provide a fluid distributor wherein a maximum cross-sectional flow area in the flow chamber is no greater than a cross-sectional flow area at the supply inlet port.
Another feature of this invention is that the flow restrictor may be positioned between the distributor outlet ports and a plurality of applicator lines, thereby facilitating creating the pressure drop and/or adjusting the fluid flow rate in a portion of each of the distributor outlet ports downstream of the distribution point.
It is an additional feature of this invention to provide for motorized and/or programmable controller to control the fluid fertilizer application rate and the fluid pressure in the system upstream of the point of fluid distribution. A flow meter, a flow restrictor and/or a flow controller, such as a motor or actuator, may be monitored and/or controlled by a programmable controller, or manually.
An additional feature is that the flow restrictor may be substantially cylindrical-shaped and positioned at least partially within an interior portion of the distributor housing to reduce the fluid pressure substantially immediately after fluid distribution.
It is a further feature of this invention that the substantially cylindrical-shaped flow restrictor may be moveable axially along a flow restrictor axis, relative to the distributor housing.
Another feature of this invention is that a substantially sleeve-shaped housing orifice ring including a plurality of orifices therein to conduct fluid may be positioned within the distributor housing to provide a surface to seal with the flow restrictor.
Still another feature of this invention is that a substantially sleeve-shaped housing orifice ring may include a plurality of slot-shaped orifices therein to conduct fluid within the distributor housing to increase the number of applicator lines which may be connected to a distributor housing.
It is a further feature of this invention that a flow restrictor seal member may be secured to the flow restrictor to shut off fluid flow through the fluid distributor when the flow restrictor is in a closed position.
It is yet another feature of this invention to provide a setting indicator secured to one or more components of the fluid distributor for indicating the position of the flow restrictor relative to the distributor housing.
It is an advantage of this invention that one or more of the flow restrictor, the flow restrictor seal member, the housing orifice ring, and/or the distributor housing may be formed from a polymer material to increase sealing effectiveness between components.
It is another advantage of this invention that existing fluid fertilizer equipment may be fitted with a fluid distributor according to this invention.
It is an advantage that a fluid distributor according to this invention may be relatively simple and economical to manufacture, install, use, repair and adjust to a particular fluid fertilizer application rate.
Another advantage of this invention is that a fluid distributor according to this invention may be useful over a wide spectrum of application rates and pressures.
It is yet another advantage of this invention that fluid fertilizer application rates may be substantially uniform across the multiple applicator distribution lines, with reduced fluid rate variability between applicators. Thereby, improvements may be realized in fertilizer efficiency, crop performance and yields, while reducing fertilizer waste, fertilizer over-concentration damage to crops, and potential environmental hazards due to nitrate formations within groundwater.
These and further objects, features, and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to figures in the accompanying drawings.